Is Aspirin Safe for Cats?

A veterinarian's advice on safe dosages of aspirin for cats with congestive heart failure.


[From Tufts January 2010 Issue]

I recently had to have my 8-year-old cat, Tasha, put to sleep after she threw a clot that paralyzed her back legs. She was in severe respiratory distress from congestive heart failure. My veterinarian said that it was probably hereditary, so we had her sibling, Gussy, tested for heart problems.

The veterinarian did an echocardiogram and said that Gussy “definitely has a bad ticker.” He said it was borderline congestive heart failure. Hearing that nearly killed me. I adopted them when they were both 8 weeks old. Now, I’m looking at losing them both.

My veterinarian prescribed giving Gussy on a quarter of a baby aspirin twice a week. Even though it’s a small dosage, I’m concerned because I keep reading how poisonous aspirin can be to cats. I understand that there are supplements available to strengthen the heart. What would you recommend? -Lauren Valyou

A: I’m sorry to hear about your troubles with Tasha and Gussy. It sounds like your cat has hypertrophic cardiomyopathy (HCM), a serious heart condition. The fact that Tasha and Gussy are siblings and are both affected certainly does suggest that hereditary factors are involved.

There are several potential outcomes for cats with HCM. Some cats die suddenly of a fatal arrhythmia (heart rhythm disturbance). Others gradually develop congestive heart failure. Some develop a blood clot that obstructs blood flow to the rear limbs, causing acute paralysis. Unfortunately, Tasha fell victim to the thromboembolism (blood clot). In order to try to prevent Gussy from suffering the same fate, veterinarians traditionally have prescribed aspirin in an attempt to inhibit platelet function and make the blood less likely to clot.

Cats have a different metabolism compared to dogs, and they do not metabolize non-steroidal anti-inflammatory drugs (like aspirin) as efficiently. As a result, some of these drugs can be quite toxic to cats (like ibuprofen), while others can be given safely, if the dosage is adjusted properly. Aspirin , at the canine dose, would make a cat sick. But when given at the proper dose (such as a baby aspirin every three days), cats do fine.

Recently, some studies have suggested that clopidogrel (Plavix) is also effective at inhibiting blood clotting, and many veterinarians and veterinary cardiologists have been prescribing clopidogrel instead of aspirin. Not because aspirin isn’t safe for cats, but because they feel it may be more effective. Ask your vet about this option rather than using holistic drugs or unproven supplements.

Arnold Plotnick, DVM
Medical Editor


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